I found this book but it talks about an SDK created by the author rather than pure simple OpenGL ES 2.0; this sounds more like a commercial to me than a good book for programming. I would like to start with just OpenGL ES 2.0 without talking about anything else: can you give me a good advice on this? A good book or on-line resource.

I'm also interested in cross platform development with OpenGL ES, in particular Android and iOS.

I'm no expert on this topic, but I developed a couple of games with a friend that were multiplatform (Android, Maemo, Linux, Windows). He did all the low level engine stuff, and based on our conversations, he pretty much didn't use any book, he did have reasonable amount of knowledge of OpenGL programming, and for GLES peculiarities, he pretty much googled for documentation and worked with that. I know this is not very helpful, but programming with FLOSS does often come to exactly that.
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Vladimir MitrovicSep 12 '12 at 18:45

yes, this is kind of the "obvious choice" but it's quite old and i can't get why there aren't other books about this.
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user827992Sep 12 '12 at 19:49

It's a few years old, yes, but so is ES 2.0 :) I can relate to your frustration with excessive self-promotion in books/tutorials, and have always preferred the "official" GL books for that very reason. That said, I'm not an ES/Android/iOS developer, so if there's a better resource out there that fits your criteria, I'll have to defer to my fellow GDSEers.
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postgoodismSep 12 '12 at 20:01